1. Technical Field
The present invention relates to an infrared detecting element, and particularly relates to an element that detects an irradiation amount of infrared rays.
2. Background Technology
Research has been made on an infrared detecting element using a micromachining technology to a silicon base plate. One of the infrared detecting elements is a bolometer-type infrared detecting element that detects change in the temperature due to infrared rays. The infrared detecting element can detect infrared rays with good sensitivity by using an insulation structure that will not release heat after the infrared detecting element is heated by infrared rays.
Patent Document 1 has disclosed a bolometer-type infrared detecting element in which a detecting section is provided in an area spaced apart from a silicon base plate. According to this document, a sacrifice layer is formed of diamond-like carbon, and a supporting section and a detecting section are formed on the sacrifice layer. Then, etching is conducted to the sacrifice layer by plasma processing including oxygen so as to form a hollow space. In this manner, the detecting section has an insulation structure. However, the detecting section is exposed to a condition of being heated for a long period of time, and exposed to a circumstance of plasma discharge for a long period of time. Consequently, the detecting section is more likely to be damaged.
If a wet process is used at the time of etching the sacrifice layer, it is possible to prevent the detecting section from being exposed to heat or plasma for a long period of time. As such a method, the following can be possible. First, a recessed portion is formed, and a protective film for protection against an etching solution is formed on the surface of the recessed portion. Next, a sacrifice layer is formed on the recessed portion, and a supporting section and a detecting section are provided on the sacrifice layer. Subsequently, the sacrifice layer is removed by being immersed in an etching solution. The etching solution is also referred to as an etchant.    Japanese Laid-open Patent Application No. 2009-192350 (Patent Document 1) is an example of the related art.